Population Growth

Population all of the individuals of a species that live together in one place at one time

Population Characteristics features that describe interactions between the population and its environment Geographic Distribution Population Density Age Structure Growth Rate

1. Geographic Distribution a population’s range or area that it inhabits

2. Population Density the number of individuals per unit area

3. Age Structure the age distribution of a population how young or old the population is generally looks like a pyramid as a population is growing

4. Growth Rate the speed of a population’s growth (or decline) affected by four factors Mortality death rate Natality birth rate

4. Growth Rate the speed of a population’s growth (or decline) affected by four factors Immigration rate of new individuals entering the population who were born outside of the population Emigration rate of individuals leaving the population for another area

Linear vs. Exponential Growth

Exponential Growth occurs when individuals continue to reproduce at a constant rate

Exponential Growth occurs under “ideal” conditions unlimited food, water, shelter, etc. protection from predators and disease

Logistic Growth occurs when a population’s growth slows or stops following exponential growth occurs because resources become less available

Carrying Capacity the largest number of individuals an environment can support over an extended period of time

So what can cause a population’s growth rate to slow down or even decline?

Limiting Factors any factor that causes population growth to decrease

Limiting Factors

Density Dependent a limiting factor that depends on population size predation competition parasitism disease

Density Independent affect all populations similarly regardless of the population size weather natural disasters human activities

Human Population Growth Historical Overview The size of the human population has increased over time. It has increased very quickly the last couple hundred years…Why??? Agriculture and Industry Reliable Food Supply Improved Sanitation Medical and Health Care

Human Population Growth Demography scientific study of human populations

Human Population Growth Demographic Transition a dramatic change in birth and death rates

Human Population Growth

Age Structure Diagram model for predicting future population growth or decline

Age Structure Diagram

Age Structure Diagram

Age Structure Diagram

Age Structure Diagram